Of course keeping your bow shoulder low as you draw the bow is desirable, as you know, so long as you don't exaggerate it. "Keep" means to maintain the same position it was in before you started the draw, not force it even lower.
However, what may be happening, and this may apply to many of the other issues you have been raising, is that because you're focusing on one thing, you forget others. Which others? Who knows? But you cannot become a good shot until you correctly execute all the elements of good form at the same time, which just takes a lot of practice and a lot of bad shots to get through.
This happens to me too, even though I've shot a bow for many years. I just returned from a tune-up with Rick Welch. As would be expected, or it would be a waste of money, he immediately saw things I wasn't aware of that I was doing (or not doing) incorrectly. In focusing on these new things, I forget to do other things I already know about. This is embarrassing for the student, but instructors are used to it, and it is a normal part of the learning process.
So I doubt if your bow shoulder is the problem, because you're focusing on it. The problem is something you're not focusing on, and you can only correct this by either getting help from someone, or through a long process of trial and error until you eventually stumble onto the problem yourself. But I don't think anyone here is going to be able to help you much without seeing you shoot, probably in a video.